The present invention relates to a calcium scoring method and system. More particularly, the present invention is concerned with a method and system for scoring calcium using a tomographic image produced by an X-ray CT system.
A tomographic image produced by an X-ray CT system is often used to score calcium. A calcium score is expressed as a product of a rank of a CT number, which is calculated from each pixel value, by the size of a field composed of pixels whose CT numbers rank the same. The calcium scoring is referred to as an Agatston-Janowtiz scoring method (refer to, for example, Non-patent Document 1).
[Non-Patent Document 1] Quantification of Coronary Artery Calcium Using Ultrafast Computed Tomography (Arthur S Agatston et al., JACC, U.S.A., 1990, Vol. 15, 4th Edition, P. 827-P. 832)
Calcium deposited on an intravascular wall obstructs circulation of blood. Scoring such calcium has a clinically significant meaning. However, according to the foregoing method, calcium in every region including bones is scored. A diagnostician has to distinguish blood vessels on the basis of his/her anatomical knowledge and then check calcium scores. This is time-consuming.